A control apparatus for an internal combustion engine which includes a turbo-supercharger and a waste gate valve that opens and closes an exhaust bypass passage that bypasses a turbine has already been disclosed in, for example, Patent Literature 1. According to the conventional control apparatus, a configuration is adopted so as to perform the following control to warm up an exhaust gas purifying catalyst that is disposed on the downstream side of the turbine after a cold startup. That is, when the internal combustion engine is in an idling state after a cold startup, the aforementioned control apparatus is configured so as to execute catalyst warm-up control (specifically, corresponds to “upstream catalyst warm-up process” in Patent Literature 1) that opens the waste gate valve and retards the ignition timing.
Meanwhile, the atmospheric pressure is low in a highland area. If the air density decreases accompanying a decrease in the atmospheric pressure, the torque that is generated by an internal combustion engine decreases. Consequently, in a highland area, it is necessary to enlarge the degree of opening of a throttle valve in order to secure an intake air amount (required intake air amount) that is required to maintain an idling speed during execution of the above described catalyst warm-up control. Consequently, a difference between the intake pressures before and after the throttle valve decreases. For this reason, in a highland area, in some cases it is difficult to perform adjustment of the aforementioned required intake air amount using the throttle valve while catalyst warm-up control is being executed.
Further, since the exhaust gas temperature rises when the ignition timing is retarded, the amount of exhaust energy that is introduced into the exhaust gas purifying catalyst can be increased. However, retarding the ignition timing leads to a decrease in the torque of the internal combustion engine. Accordingly, in a highland area, in a case where maintaining the idling speed is prioritized when it has become difficult to secure the required intake air amount using the throttle valve during execution of catalyst warm-up control, it is difficult to sufficiently retard the ignition timing. Consequently, it is difficult to maintain the amount of energy that is introduced to the exhaust gas purifying catalyst at a high level. Thus, with respect to the catalyst warm-up control disclosed in the aforementioned Patent Literature 1, there is a concern that in a highland area where the atmospheric pressure is low, a situation may arise in which an exhaust gas purifying catalyst cannot be warmed up sufficiently.
Including the above described document, the applicant is aware of the following documents as related art of the present invention.